JP5987790B2 - Electrical steel sheet with insulating coating and method for producing the same - Google Patents

Description

  The present invention relates to an electromagnetic steel sheet with an insulating coating and a method for producing the same. The electrical steel sheet with an insulating coating of the present invention is excellent in all of insulation, tension pad resistance and punching properties even if the insulating coating does not contain a chromium compound.

  Electrical steel sheets with insulating coatings used for motors, transformers, and the like are required to have various characteristics such as punchability as well as interlayer resistance that is insulation performance between stacked steel sheets. Moreover, since the electrical steel sheet with an insulating coating is used for various applications, various characteristics are required depending on the application. For example, when slitting a coil or the like, it is required to have resistance to peeling of the insulating coating when the surface of the electromagnetic steel plate with insulating coating is rubbed with a felt-like tension pad used to hold the steel plate, so-called tension pad resistance.

  Insulating coatings formed on the surface of electrical steel sheets can be broadly classified as follows: (1) An inorganic coating that emphasizes weldability and heat resistance and resists strain relief annealing, and (2) Stress relief annealing for both punchability and weldability. It is classified into three types: a resin-containing inorganic coating (that is, a semi-organic coating) that can withstand heat resistance, and (3) an organic coating that cannot be subjected to strain relief annealing in special applications. And the insulating film which can endure distortion removal annealing as a general purpose product is an insulating film containing the inorganic component shown in said (1) and (2). Conventionally, an insulating coating containing an inorganic component generally contains a chromium compound.

  However, recently, environmental awareness has increased, and in the field of electrical steel sheets, a chromate-free product having an insulating coating that does not contain a chromium compound on the surface is demanded by customers. Techniques for forming an insulating coating corresponding to the above (2) by applying a surface treatment agent that does not contain a chromium compound and contains both an organic component and an inorganic component to the surface of the electrical steel sheet include the following. .

  In Patent Document 1, an organic substance composed of one or more of water-soluble or emulsion type resins is added to an inorganic colloidal substance composed of one or more of colloidal silica, alumina sol, and zirconia sol. A technique for forming an insulating film having excellent corrosion resistance before strain relief annealing using an aqueous solution as a surface treatment agent is described.

Japanese Patent Laid-Open No. 10-46350

  However, the conventional technology described above cannot provide an electrical steel sheet with an insulating coating that has good insulation, tension pad resistance, and punchability.

  Therefore, in view of the above problems, the present invention provides an electrical steel sheet with an insulating coating that is excellent in all of insulation, tension pad resistance and punching performance without including a chromium compound in the insulating coating, and a method for producing the same. Objective.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, it has been found that the skewness Rsk on the surface of the electromagnetic steel sheet has a great influence on properties such as the insulation properties of the electromagnetic steel sheet with an insulating coating, and the present invention has been completed. More specifically, the gist configuration of the present invention capable of achieving the above object is as follows.

(1) Electrical steel sheet, selected from trialkoxysilane represented by the following general formula (I), dialkoxysilane represented by the following general formula (II), and tetraalkoxysilane represented by the following general formula (III) An insulating coating formed on the surface of the electrical steel sheet using a surface treatment agent containing at least one silane compound (A), a silane coupling agent (B), and silica particles (C); An electrical steel sheet with an insulating coating, wherein the electrical steel sheet has a skewness Rsk of 1.00 or less.
X ¹ Si (OR ¹ ) ₃ (I)
(X ² ) ₂ Si (OR ² ) ₂ (II)
Si (OR ³ ) ₄ (III)
(X ¹ and X ^{2 in} the above general formula are hydrogen, an alkyl group or a phenyl group. X ² may be the same or different from each other. R ¹ , R ² and R ³ are alkyl groups. R ¹ may be the same or different, R ² may be the same or different, and R ³ may be the same or different.
(2) an Rsk adjusting step of setting the surface skewness Rsk of the electrical steel sheet to 1.00 or less, a trialkoxysilane represented by the following general formula (I), a dialkoxysilane represented by the following general formula (II), and A surface treatment agent containing at least one silane compound (A) selected from tetraalkoxysilanes represented by the following general formula (III), a silane coupling agent (B), and silica particles (C) is used. And an insulating film forming step of forming an insulating film on the surface of the electromagnetic steel sheet after the Rsk adjusting step.
X ¹ Si (OR ¹ ) ₃ (I)
(X ² ) ₂ Si (OR ² ) ₂ (II)
Si (OR ³ ) ₄ (III)
(X ¹ and X ^{2 in} the above general formula are hydrogen, an alkyl group or a phenyl group. X ² may be the same or different from each other. R ¹ , R ² and R ³ are alkyl groups. R ¹ may be the same or different, R ² may be the same or different, and R ³ may be the same or different.

  ADVANTAGE OF THE INVENTION According to this invention, although an insulating film does not contain a chromium compound, the electrical steel sheet with an insulating film which is excellent in insulation, tension pad property, and punching property is obtained.

  Hereinafter, embodiments of the present invention will be specifically described. In addition, this invention is not limited to the following embodiment.

Electrical steel sheet with insulation coating The electrical steel sheet with insulation coating of the present invention has an electrical steel sheet and an insulation coating formed on the surface of the electrical steel sheet. Hereinafter, the electromagnetic steel sheet and the insulating coating will be described.

<Electromagnetic steel sheet>
In the present invention, the electromagnetic steel sheet as a material is not particularly limited, and any conventionally known steel sheet can be used. That is, so-called soft iron plates (electric iron plates) with high magnetic flux density, general cold-rolled steel plates such as SPCC, and non-oriented electrical steel plates containing Si or Al to increase specific resistance are advantageously suitable. .

  Moreover, although the component composition of an electromagnetic steel plate is not specifically limited, the component composition of a normal electromagnetic steel plate is Si: 1 to 4.5%, and the balance is Fe and inevitable impurities. In addition, the electromagnetic steel sheet has C: 0.01% or less, Mn: 0.02-3%, Cr: 0.8% or less, Cu: 0.01-2%, P: 0.03-0.2% N: 0.005% or less, Mo: 0.005-0.1%, Sn: 0.005-0.2%, Sb: 0.005-0.2%, S: 0.005% or less, and Al: At least one selected from 0.001 to 3% may be contained.

  The electrical steel sheet used in the present invention has a skewness Rsk of 1.00 or less on the surface of the electrical steel sheet. By setting the skewness Rsk to 1.00 or less, the interlayer resistance (resistance between steel sheets when magnetic steel sheets with insulating coatings are overlapped) is unlikely to decrease.

  Conventionally, the relationship between the skewness of the steel sheet surface and the interlayer resistance has not been known, but the present inventors have different interlayer resistances while the Ra of the steel sheet surface and the thickness of the insulating coating formed on the steel sheet surface are the same. In some cases, and in investigating the cause of this phenomenon, the relationship between the skewness Rsk on the steel sheet surface and the interlayer resistance was found.

  Here, the skewness Rsk means a value obtained by measuring a three-dimensional shape using an optical interference surface shape measuring device as described in the examples.

  In particular, as in the present invention, when the electrical steel sheet having a surface skewness Rsk of 1.00 or less and a specific insulating film to be described later are combined, the electrical steel sheet with an insulating film does not contain a chromium compound. Nevertheless, it has excellent insulation, tension pad resistance, and punchability.

  It is necessary to adjust the skewness Rsk in order to obtain an excellent electrical steel sheet with an insulating coating, and the surface roughness Ra of the steel sheet surface is not particularly limited. With the normal surface roughness, the effects of the present invention can be obtained without problems. The normal surface roughness Ra is 0.80 μm or less. Here, the surface roughness Ra means a value obtained by measuring a three-dimensional shape using an optical interference surface shape measuring device, similarly to the skewness Rsk.

<Insulating coating>
The insulating coating in the present invention is formed on the surface of the electrical steel sheet using a surface treating agent containing a silane compound (A), a silane coupling agent (B), and silica particles (C).

  In the surface treating agent used in the present invention, a combination of at least one silane compound (A) selected from trialkoxysilane, dialkoxysilane and tetraalkoxysilane and a silane coupling agent (B) is used as the organic component. . The combination of such a silane compound (A) and a silane coupling agent (B) increases the corrosion resistance of the electrical steel sheet with an insulating coating.

  In addition, in the insulating coating only of the silane component derived from the silane compound (A) and the silane coupling agent (B), the film thickness is reduced at the minute uneven portions on the surface of the electromagnetic steel sheet, and the pressure applied to the insulating coating during use. In some cases, the interlayer resistance may be too low. In addition, in the insulating coating composed only of the silane component derived from the silane compound (A) and the silane coupling agent (B), the film is easily damaged and the interlayer resistance may be lowered. However, if the silica particles (C) are used, the insulating coating can easily secure a certain thickness, and therefore, the problem that the interlayer resistance is excessively lowered even when pressure is applied to the insulating coating during use can be suppressed. Moreover, if the silica particles (C) are used, the insulating coating can be hardly damaged, so that it is easy to suppress a decrease in interlayer resistance. If silica particles (C) are used, for the same reason, when the magnetic steel sheets with insulating coatings are stacked and subjected to pressure annealing, the steel loss is unlikely to increase due to contact between the steel sheets. The sticking resistance is also improved.

  If a surface treatment agent containing the above components (A) to (C) is used to form an insulating film on the magnetic steel sheet, the insulating film does not contain a chromium compound, but the insulation, tension pad resistance, In addition to the effect of improving punchability, the effect of improving corrosion resistance, sticking resistance, and the like is also obtained. Therefore, if the specific surface treatment agent is used, an excellent electrical steel sheet with an insulating coating can be obtained.

  Hereinafter, the silane compound (A), the silane coupling agent (B), and the silica particles (C) will be described more specifically.

  The silane compound (A) is selected from trialkoxysilane represented by the general formula (I), dialkoxysilane represented by the general formula (II), and tetraalkoxysilane represented by the general formula (III). At least one.

The trialkoxysilane represented by the general formula (I) is X ¹ Si (OR ¹ ) ₃ . X ¹ is a non-reactive substituent selected from hydrogen, an alkyl group, and a phenyl group. When X ¹ is an alkyl group, X ¹ is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 3 carbon atoms. R ¹ is an alkyl group, preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 2 carbon atoms. Here, one molecule of trialkoxysilane has three R ^{1 s} , and these three R ^{1 s} may be the same or different from each other. Specific examples of trialkoxysilanes represented by the general formula (I) include methyltrimethoxysilane, ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, and these Examples include hydrolysates. In the present invention, trialkoxysilane having an alkyl group is preferable from the viewpoint of further improving the corrosion resistance of the electrical steel sheet with an insulating coating. The surface treatment agent may contain two or more kinds of the trialkoxysilane.

The dialkoxysilane represented by the general formula (II) is (X ² ) ₂ Si (OR ² ) ₂ . Here, X ² is a non-reactive substituent selected from hydrogen, alkyl group and phenyl group. X ² is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 3 carbon atoms. Here, although one molecule of dialkoxysilane has two X ² , the two X ² may be the same or different from each other. R ² is an alkyl group, preferably a linear or branched alkyl group having 1 to 4 carbon atoms, more preferably a linear or branched alkyl group having 1 to 2 carbon atoms. Here, one molecule of dialkoxysilane has two R ^{2 s} , and these two R ^{2 s} may be the same or different from each other. Specific examples of dialkoxysilanes represented by the general formula (II) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane and hydrolysates thereof. In the present invention, a dialkoxysilane having an alkyl group is preferred from the viewpoint that the corrosion resistance of the electrical steel sheet with an insulating coating is more excellent. Further, the surface treating agent may contain two or more kinds of the above dialkoxysilanes.

The tetraalkoxysilane represented by the general formula (III) is Si (OR ³ ) ₄ . Here, R ³ is an alkyl group, preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 2 carbon atoms. Here, one molecule of tetraalkoxysilane has four R ^{3 s} , and these four R ^{3 s} may be the same or different from each other. Specific examples of the tetraalkoxysilane represented by the general formula (III) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and hydrolysates thereof. In the present invention, tetraethoxysilane and tetramethoxysilane are preferred from the viewpoint that the corrosion resistance of the electrical steel sheet with an insulating coating is more excellent. Further, the surface treating agent may contain two or more kinds of the above tetraalkoxysilanes.

  Although content of the silane compound (A) in a surface treating agent is not specifically limited, It is preferable that it is 1-30 mass% with respect to the total solid of a surface treating agent. If the content of the silane compound (A) is 1% by mass or more, it is preferable because the TIG adhesion of the electrical steel sheet is increased. If the content of the silane compound (A) is 30% by mass or less, a silane coupling agent ( Since B) is the main component, it is preferable because the toughness of the insulating coating can be sufficiently obtained.

Type of silane coupling agent (B) is not particularly limited, for example, the general formula _{^{X 3 Si (R 4) n}} (OR 5) 3-n ( where n ranges from 0 to 2) those represented by the Can be preferably used. Here, X ³ is at least one reactive functional group selected from an active hydrogen-containing amino group, an epoxy group, a mercapto group, and a methacryloxy group. R ⁴ is an alkyl group, preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 2 carbon atoms. When n is 2, one silane coupling agent has two R ^{4 s} . In this case, the two R ^{4 s} may be the same or different from each other. OR ⁵ is an arbitrary hydrolyzable group, R ⁵ is, for example, an alkyl group, preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and more preferably a linear chain having 1 to 2 carbon atoms. Or it is a branched alkyl group. R ⁵ may be, for example, an acyl group (—COR ⁶ ). R ⁶ is preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 2 carbon atoms. When n is 1 or less, one molecule of the silane coupling agent has 2 or more (OR ⁵ ). At this time, 2 or more (OR ⁵ ) may be the same or different from each other. Specific examples of the silane coupling agent (B) include N- (aminoethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxy. Examples thereof include propylmethyldimethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltriethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and hydrolysates thereof. In this invention, the silane coupling agent which has an amino group or an epoxy group from a viewpoint that the corrosion resistance of the electrical steel sheet with an insulation film is more excellent is preferable. Further, the surface treatment agent may contain two or more silane coupling agents.

  Although content of a silane coupling agent (B) is not specifically limited, Mass ratio (A / B) of a silane compound (A) and a silane coupling agent (B) is in the range of 0.05-1.0. It is preferable to contain a silane coupling agent (B). By using a sufficient amount of the silane coupling agent (B) so that the mass ratio (A / B) is 1.0 or less, the toughness of the insulating coating can be sufficiently increased. As a result, it is possible to obtain an electrical steel sheet with an insulating coating having more sufficient tension pad resistance. Moreover, if mass ratio is 0.05 or more, since TIG weldability of the electromagnetic steel plate with an insulating film is fully obtained, it is preferable.

  The type of silica particles (C) is not particularly limited, and colloidal silica or dry silica (also referred to as vapor phase silica) can be used. Examples of colloidal silica include Snowtex C, N, 20, OS, OXS, OL (all trade names) manufactured by Nissan Chemical Co., Ltd., and the like. Examples of dry silica include AEROSIL 50, 130, 200, 300, and 380 (all trade names) manufactured by Nippon Aerosil Co., Ltd. In this invention, 1 or more types of these can be used as a silica particle (C).

  Moreover, you may use the plate-shaped silica particle which has anisotropy as a silica particle (C). Examples of the plate-like silica include Sun Lovely manufactured by AGC S-Itech Co., Ltd.

  The compound form of the silica particles (C) is not limited to amorphous and crystalline, and the manufacturing method is not limited. The silica particles (C) may be subjected to a surface treatment for enhancing dispersibility and reactivity with silane.

  As the silica particles (C), it is effective to use plate-like silica from the viewpoint of enhancing the insulation properties of the electromagnetic steel sheet with an insulating coating, but according to the present invention, inexpensive colloidal without using plate-like silica. Even when silica or dry silica is used, an electrical steel sheet with an insulating coating having good insulation can be obtained.

  Moreover, in this invention, it is preferable to use together plate-like silica and colloidal silica. By using together, the insulation of an electromagnetic steel plate with an insulating coating can be remarkably improved. When using together, it is preferable to make plate silica and colloidal silica into the range of 1 or less by mass ratio (mass of plate silica / mass of colloidal silica).

  The size of the silica particles (C) is not particularly limited, but it is preferable that the average particle diameter measured by a method called laser diffraction / scattering method is in the range of 10 to 200 nm because interlayer resistance and weldability can be secured. .

  The content of the silica particles (C) is not particularly limited, but it is preferably 5 to 40% by mass with respect to the total solid content of the surface treatment agent because interlayer resistance, weldability, and sticking resistance can be ensured. .

  Furthermore, a lubricant (D) can be added to the surface treatment agent used in the present invention in order to further improve the tension pad resistance. Examples of the lubricant (D) include solid lubricants such as polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax, carnauba wax, paraffin wax, montan wax, rice wax, Teflon (registered trademark) wax, carbon disulfide, and graphite. It is done. Moreover, you may use a nonionic acrylic resin as a lubricant (D). Nonionic acrylic resins include, for example, nonionic surfactants (emulsifiers) that have polyethylene oxide or polypropylene oxide on the structure of vinyl monomers such as acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, and styrene. An acrylic resin emulsified with a nonionic emulsifier, such as an aqueous emulsion obtained by emulsion polymerization in water. One or more of these solid lubricants can be used.

  Although content of a lubricant (D) is not specifically limited, It is preferable to contain 1.0-15.0 mass% with respect to the total solid of a surface treating agent, and 1.5-13.0 mass% is more. preferable. When the content is 1.0% by mass or more, the tension pad resistance can be further improved, and when the content is 15.0% by mass or less, sufficient TIG weldability can be maintained.

  The surface treatment agent can be obtained by mixing the above-described components in water such as deionized water or distilled water. What is necessary is just to select the solid content ratio of a surface treating agent suitably. Further, alcohol, ketone, cellosolve water-soluble solvent, surfactant, antifoaming agent, leveling agent, pH adjuster, antibacterial and antifungal agent and the like may be added to the surface treatment agent as necessary. . By adding these, the drying property, coating appearance, workability, and designability of the surface treatment agent are improved. However, it is important to add them to such an extent that the quality obtained in the present invention is not impaired, and the addition amount is less than 5% by mass based on the total solid content of the surface treatment agent.

  The adhesion amount of the insulating film formed using the surface treatment agent as described above is not particularly limited. For example, the adhesion amount of the insulating coating can be appropriately set according to the surface roughness Ra. Specifically, if the surface roughness Ra is made larger, it is preferable to increase the amount of adhesion, and if the surface roughness Ra is made smaller, the amount of adhesion can be made smaller.

The amount of coating coating representing the amount of insulating coating formed on the electrical steel sheet is not particularly limited, but considering that the surface roughness Ra of a normal electrical steel sheet is in the range of 0.2 to 0.8 μm, It is preferable to set it as about 0.05-5 g / m < ² >. If the amount of coating is within this range, the effect of improving the insulation, tension pad resistance and punchability can be sufficiently enhanced. A more preferable range of the coating amount is 0.1 to 3.0 g / m ² . The most preferable range of the coating amount is 0.3 to 3.0 g / m ² .

In addition, according to the present invention, it is possible to obtain an electrical steel sheet with an insulating coating that is superior in insulation, tension pad resistance, and punchability, while having a smaller coating amount than conventional. For example, if the surface roughness Rsk on the surface of the electromagnetic steel sheet is 1.00 μm or less, even if the adhesion amount is adjusted to 0.30 to 0.50 g / m ² , an excellent steel sheet with an insulating coating is obtained.

  The total coating amount, that is, the total solid mass of the insulating coating, can be measured from the decrease in weight after removing the coating by alkali peeling. Moreover, when there is little film adhesion amount, it can measure from the calibration curve obtained by measuring a standard sample with known adhesion amount measured by the alkali peeling method by fluorescent X-ray analysis.

  The insulating coating is preferably formed on both sides of the electrical steel sheet, but may be only on one side depending on the purpose. In addition, another insulating film may be formed on the other surface.

The manufacturing method of an electromagnetic steel plate with an insulating coating The manufacturing method of this invention has the Rsk adjustment process which adjusts the skewness Rsk of the surface of an electromagnetic steel plate, and the insulating coating formation process which forms an insulating coating on the steel plate surface after Rsk adjustment.

<Rsk adjustment process>
The Rsk adjustment step is performed during the production of the above-described electrical steel sheet used in the present invention. In this invention, a general method can be employ | adopted for the manufacturing method of an electromagnetic steel plate. For example, in the case of a grain-oriented electrical steel sheet, a steel material (slab) adjusted to a predetermined component composition is melted to form a steel material (slab), and then the slab is hot-rolled to form a hot-rolled sheet. Hot-rolled sheet annealing is performed, and cold rolling is performed once or two or more times with intermediate annealing in between to obtain a cold-rolled sheet having a final thickness. Then, after performing recrystallization annealing which served as decarburization, the method of performing final annealing which served as secondary recrystallization and purification is common. Moreover, in the case of a non-oriented electrical steel sheet, after making the molten steel adjusted to the desired component composition into a steel raw material (slab) by a continuous casting method, this is hot-rolled to make a hot-rolled sheet. After this, if necessary, hot-rolled sheet annealing is performed, and if necessary, intermediate rolling is performed, and then cold rolling is performed one or more times to finish the final sheet thickness, and the obtained cold-rolled sheet is subjected to continuous annealing. Is common.

  For example, the skewness Rsk on the surface of the electromagnetic steel sheet can be adjusted to a desired range by performing the Rsk adjustment step during the cold rolling for making the electromagnetic steel sheet the final thickness. In the final cold rolling, the roll roughness and the roll pressure play important roles in order to adjust the skewness Rsk on the surface of the electrical steel sheet. The method for determining the conditions of the roll roughness and the roll pressure is not particularly limited. For example, when the skewness Rsk on the surface of the electromagnetic steel sheet exceeds 1.00, the roll roughness is decreased and the roll pressure is increased. By adjusting the roll roughness and the roll pressure, the skewness Rsk on the surface of the electromagnetic steel sheet can be adjusted to 1.00 or less.

<Insulating film formation process>
The insulating coating forming step is a step of forming an insulating coating on the surface of the electrical steel sheet by applying a surface treatment agent to the surface of the electrical steel sheet after the Rsk adjusting step and drying, preferably heating and drying.

  Examples of the method for applying the surface treatment agent to the surface of the electrical steel sheet include a roll coating method, a bar coating method, a dipping method, a spray coating method, and the like, and an optimal method is appropriately selected depending on the shape of the electrical steel sheet to be processed. . More specifically, for example, if the magnetic steel sheet is a sheet, a roll coating method, a bar coating method, or a spray coating method can be selected. The spray coating method is a method of adjusting the coating amount by spraying a surface treatment agent on a magnetic steel sheet and blowing a roll squeeze or gas at a high pressure. If the electromagnetic steel sheet is a molded product, a method of adjusting the coating amount by immersing it in the surface treatment agent and pulling it up, and blowing off the excess surface treatment agent with compressed air is selected. In addition, the adhesion amount of an insulating film can be adjusted by adjusting the application amount.

  The heating temperature (maximum ultimate plate temperature) when drying the surface treatment agent applied to the surface of the electromagnetic steel sheet is usually 80 to 350 ° C, and more preferably 100 to 300 ° C. If the heating temperature is 80 ° C. or higher, moisture as the main solvent does not remain in the insulating coating, and if the heating temperature is 350 ° C. or lower, the generation of cracks in the insulating coating is suppressed. And so on. The heating time is appropriately selected according to the type of electromagnetic steel sheet used. In addition, from the viewpoint of productivity and the like, 0.1 to 60 seconds are preferable, and 1 to 30 seconds are more preferable.

  In addition, the pretreatment of the electromagnetic steel sheet is not particularly limited, and a pretreatment intended to remove oil, dirt and / or oxide film of the electromagnetic steel sheet as necessary before applying the surface treatment agent. You may give to an electromagnetic steel plate. Electrical steel sheets are often coated with rust-preventive oil for rust-prevention purposes, and even when rust-preventive oil is not applied, there may be dirt or oxide films attached during work. . In addition, these oil coatings, dirt or oxide films hinder the wettability of the surface of the electrical steel sheet and hinder the formation of a uniform insulating film, but by applying the above pretreatment, The surface is cleaned, and it becomes easy to wet uniformly. When there is no oil, dirt or oxide film on the surface of the electrical steel sheet, and the surface treatment agent gets wet uniformly, the pretreatment step is not particularly necessary. The pretreatment method is not particularly limited, and examples thereof include hot water washing, solvent washing, degreasing treatment with alkali, and pickling treatment with hydrochloric acid, sulfuric acid, phosphoric acid, and the like.

In addition, the electrical steel sheet with an insulating coating can be subjected to strain relief annealing to remove, for example, strain due to punching. As a preferable strain relief annealing atmosphere, an atmosphere in which iron is not easily oxidized, such as an N ₂ atmosphere or a DX gas atmosphere, is applied. Here, the dew point is set high, for example, Dp: about 5 to 60 ° C., and the corrosion resistance can be further improved by slightly oxidizing the surface and the cut end face. Moreover, as preferable strain relief annealing temperature, it is 700-900 degreeC, More preferably, it is 700-800 degreeC. The holding time of the strain relief annealing temperature is preferably longer, for example, 2 hours or longer.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(1) Material An electromagnetic steel plate [A230 (JIS C 2552 (2000))] having a thickness of 0.5 mm was used as a test material. In addition, the said electromagnetic steel sheet consists of Si: 1 to 4.5%, and remainder consists of Fe and an unavoidable impurity.

(2) Adjustment of skewness Rsk As shown in Table 1, in this example, many electrical steel sheets having different surface skewness Rsk were used. The skewness Rsk was adjusted by changing the roll pressure and the roll roughness during cold rolling to obtain a final sheet thickness of 0.5 mm.

(3) Measurement of Ra and skewness Rsk The measurement of the skewness Rsk and surface roughness Ra of the surface of the electromagnetic steel sheet was obtained by measuring a three-dimensional shape using an optical interference surface shape measuring device (manufactured by Cannon, Zygo). The results are shown in Table 1.

(4) Surface treatment agent The component (A) shown in Table 1 and trifunctionality so that the content of the component (A) shown in Table 1 is 75% by mass (relative to the total solid content of the surface treatment agent). Containing component (C) shown in Table 1 so that the mass ratio of epoxy-based silane coupling agent (B) (3-glycidoxypropyltrimethoxysilane) having a SiO ₂ ratio of 27% is 1: 4 The mixture was mixed in water so that the amount was 25% by mass (relative to the total solid content of the surface treatment agent), and stirred for 30 minutes to obtain a surface treatment agent. A1 to A4 representing the component (A) in Table 1 are A1 is tetramethoxysilane, A2 is methyltrimethoxysilane, A3 is dimethyldimethoxysilane, and A4 is phenyltrimethoxysilane.

(5) Treatment method After performing annealing to obtain a predetermined material in the continuous annealing line, a surface treatment agent is applied by roll coater coating when the steel sheet is cooled, and the maximum plate temperature is 140 in an oven. It dried so that it might become ° C, and formed the insulating film of the amount of coating adhesion per side shown in Table 1 on both surfaces, and it was set as the test board. As a roll coater condition, a full reverse system was used with three rolls. The drying temperature indicates the temperature reached on the test plate surface.

Evaluation of Electrical Steel Sheet with Insulating Coating The following methods were used to evaluate interlayer resistance, tension pad resistance, punchability, corrosion resistance, and sticking resistance of the electrical steel sheet with insulating coating (test plate). The evaluation results are shown in Table 1.

(1) Interlayer resistance Interlayer resistance (Ω · cm ² / sheet) was measured according to JIS C2550 using a commercially available interlayer resistance tester having a contact. An average value of 10-point measurement was determined to be 1.5 Ω · cm ² / sheet or more.

(2) Tension pad resistance (rubbing film remaining rate)
Using a tension pad having an area of 10 mm × 10 mm, a load of 24.5 N (2.5 kgf) was applied with a rubbing tester manufactured by Taihei Rika Kogyo Co., Ltd., and the test plate surface was rubbed 100 times. The amount of adhesion between the rubbed part and the vicinity thereof was measured, and the remaining ratio of the insulating film after 100 reciprocations was calculated. The adhesion amount of the insulating coating was obtained from a calibration curve obtained by measuring the fluorescent X-ray intensity of Si and using a standard plate with a known adhesion amount. A coating residual amount of 85.0% or more was considered good.

(3) Punching property The test plate was punched using a 15 mmφ steel die until the burr height reached 50 μm, and the number of punches was evaluated.
(Criteria)
○: 1 million times or more △: 300,000 times or more, less than 1 million times ×: less than 300,000 times
(4) Corrosion resistance A wet test (50 ° C., relative humidity ≧ 98%) was performed on the test plate, the red rust generation rate after 48 hours was visually observed, and the area ratio of the area where the red rust was generated was evaluated. The area ratio is a percentage of the total area of rust generation relative to the total area observed visually.
(Criteria)
◎: Area ratio less than 20% ○: Area ratio 20% or more and less than 40% △: Area ratio 40% or more and less than 60% ×: Area ratio 60% or more (5) Sticking resistance 10 sheets of 50 mm square test plates are stacked. Annealing was performed at 750 ° C. for 2 hours under a nitrogen atmosphere while applying a load of 20 kPa (200 g / cm ² ). Then, a weight of 500 g was dropped on the test plate after annealing, and the drop height when dividing into five was investigated.
(Criteria)
◎: 10 cm or less ○: 10 cm or more, 15 cm or less Δ: 15 cm or more, 30 cm or less ×: 30 cm or more

  From the results of the invention example having a skewness Rsk of 1.00 or less on the surface of the electromagnetic steel sheet, the comparative example exceeding 1.00, and the comparative example using the surface treatment agent outside the scope of the present invention, the skewness of the steel sheet surface was made 1.00 or less. By combining this with a specific insulating film, an insulating steel sheet with an insulating film excellent in insulation, tension pad resistance, and punchability can be obtained even though the insulating film does not contain a chromium compound.

  From invention examples using colloidal silica (No. 9 to 12), invention examples using dry silica (No. 13 to 16), invention examples using plate silica (No. 17 to 20), plate silica It was confirmed that even when other colloidal silica or dry silica was used, an electromagnetic steel sheet with an insulating coating having the same performance as that obtained when plate-like silica was used was obtained.

  From invention example (No. 22) of combined use of colloidal silica and plate-like silica, invention example (No. 10) of using colloidal silica alone, invention example (No. 18) of using plate-like silica alone, colloidal silica and plate-like It was confirmed that the insulating property was remarkably increased by the combined use of silica.

  As described above, according to the present invention, an electrical steel sheet with an insulating coating excellent in interlayer resistance, tension pad resistance, and punchability can be provided. Moreover, there was no part in which other performances, such as corrosion resistance, were remarkably inferior compared with the prior art, and especially the sticking resistance showed the value higher than the prior art.

Claims (2)

Electrical steel sheet,
At least one silane selected from trialkoxysilane represented by the following general formula (I), dialkoxysilane represented by the following general formula (II), and tetraalkoxysilane represented by the following general formula (III) compound (a), a silane coupling agent (B), and using a surface treatment agent comprising the silica particles (C), the electromagnetic steel sheet formed on the surface Ri name is coating adhesion amount from 0.30 to 0 An insulating coating that is .61 g / m ² ,
Wherein Ri der skewness Rsk is below 1.00 of the surface of the electrical steel sheet,
Insulation coating with an electromagnetic steel sheet interlayer resistance characterized der Rukoto 1.5Ω · cm 2 ^/ sheet or more.
X ¹ Si (OR ¹ ) ₃ (I)
(X ² ) ₂ Si (OR ² ) ₂ (II)
Si (OR ³ ) ₄ (III)
(X ¹ and X ^{2 in} the above general formula are hydrogen, an alkyl group or a phenyl group. X ² may be the same or different from each other. R ¹ , R ² and R ³ are alkyl groups. R ¹ may be the same or different, R ² may be the same or different, and R ³ may be the same or different. Interlayer resistance is a process for the preparation of 1.5Ω · cm 2 ^/ sheet or more der Ru insulation coating with an electromagnetic steel sheet,
An Rsk adjustment step of setting the skewness Rsk of the surface of the electrical steel sheet to 1.00 or less;
At least one silane selected from trialkoxysilane represented by the following general formula (I), dialkoxysilane represented by the following general formula (II), and tetraalkoxysilane represented by the following general formula (III) Using the surface treatment agent containing the compound (A), the silane coupling agent (B), and the silica particles (C), the coating adhesion amount is 0.30 to the surface of the electrical steel sheet after the Rsk adjustment step. manufacturing method of the insulating film with an electromagnetic steel sheet characterized by having an insulating film forming step of forming an insulating film of 0.61 g / m ^2, a.
X ¹ Si (OR ¹ ) ₃ (I)
(X ² ) ₂ Si (OR ² ) ₂ (II)
Si (OR ³ ) ₄ (III)
(X ¹ and X ^{2 in} the above general formula are hydrogen, an alkyl group or a phenyl group. X ² may be the same or different from each other. R ¹ , R ² and R ³ are alkyl groups. R ¹ may be the same or different, R ² may be the same or different, and R ³ may be the same or different.